Electric discharge device for highfrequency oscillations



P 1951 A M. SKELLETT ELECTRIC DISCHARGE DEVICE FOR HIGH-FREQUENCY OSCILLATIONS Filed March 23, 1944 FIG.

FIG. 3 K7 26' Am; I vvv IVV vvv V Il r 9 3. 24- l/ 1/ Sr A'A Av AVA Av VA Av A A'l' ACZEEZDA SOURCE *28 /N VE N TOR AM. SKELLETT 8) 04am 7M ATTORNEY Because of the potentiometer interconnection of the field electrodes 23, output electrodes II and I2 and collector electrode 24 by the resistors 26 and the symmetry of the electrodes about the collector electrode 24, it will be seen that there is established in the region bounded by the output electrodes a circularly symmetrical electric field having a negative gradient of form determined by the resistors 26. The electrons projected from the electron gun are injected into this region adjacent the periphery thereof and in the direction substantially tangent to the field. Inasmuch as the output electrodes and the accelerating electrode H are both at direct current ground potential, the Velocity of the injected electrons, at the point of entry of the electrons into the electric field, will not be changed as they enter the field at this point. When the device is oscillating, inasmuch as the several field electrodes are coupled capacitively to the output electrodes by the mica members 22; the field in the region noted varies as a whole in accordance with the oscillating potentials appearing on the output electrodes.

It is apparent that the trajectoriesof the electrons in the region bounded by the output electrodes will be dependent upon the radial gradient of the electric field. In accordance with one feature of this invention, the field electrodes 23 are correlated with one another and the output electrodes and collector electrode 24 so that many of the electrons injected into the region aforenoted traverse substantially circular paths of successively decreasing radii and in such manner as to contribute energy to the oscillating circuit and, thus, to sustain oscillations. The principles involved in this correlationwill be understood from the following considerations.

The negative radial gradient of the direct current electric field in the region bounded by the output electrodes II and I2 may be designated as E or where r is the radius and U is the voltage at any radius r. If an electron is projected into this field initially tangentially thereto and has the proper velocity, it will follow a circular path over which U is constant and, for these conditions, the centrifugal and centripetal forces acting upon the electron are equal. Mathematically expressed r=radius of the path. m=electron mass. v=electron velocity. e electron charge.

The electron velocity in terms of the accelerating voltage is given by where V=the accelerating voltage necessary to give the electron the velocity 1). By substitution in Equation 1 v 4 The time required for an electron to complete one revolution in the field is expressed by where T=the time of one revolution and f=frequency. From Equations 2 and 4, it follows that where for V in practical volts.

From Equation 5 it will be seen that if the period of revolution of an electron in the field is to be independent of the radius 1, that is if this period is to be the same for all values of r, the voltage at any point in the field must vary as the square of the radius. The requisite gradient for establishing such a field is determinable from Equations 3 and 5 thus:

is important in determining the velocity of the injected electrons. They are accelerated by a positive voltage V between the cathode l5 and anode I! that is numerically equal to the negative potential U of the field at the place where they enter. For the case cited above these volt;- ages, obtained from the source 28, are V=+1,000 and U=1,000 volts. 7 v

Hence, in a device of the construction illustrated in Figs. 1 and 2, the field requisite for attainment of the condition of a constant period'of revolution of electrons about the axis in which the collector electrode 24 lies, for all values of radius is realized by constructing the resistances 26 to produce this relation between voltagean'd radius, for a given frequency, j, that is the frequency to which the oscillatory circuit 2T is tuned, expressed by Equation 6 supra. I

The operation of the device shown'in the drawing, as an oscillator is as follows: When the but put electrode II is positive with respect to the electron gun, that is during the positive half cycle of the oscillation, electrons from the gun are projected into the region bounded by the output electrodes with a velocity, in volts, substantially equal to the field voltage U at the point of .injection of the electrons into the region They will be accelerated to a velocity too great to traverse a circular path and thus will flow to and be collected by the collector electrode 20.

However, when the output electrode-l I. is negative, that islduring the negative half cycle of the asemoe'ea oscillation thereof, the injected 'electrons are Ere tarded 'upon entering into the fiel'd sovithat their velocity will be substantially equal :to that corresponding to the Voltageat-their point of entry into the field. Consequently, the electrons will follow a substantially circular path-"and one half cycle later will arrive at the gap 44 at a-point substantially 180 degrees from the point of their initial entrance into the field. At this tim'ei that is one half cycle after the initial entry of the elec trons into the region bounded by the output electrodes, the electrode [2 swings'negative. Hence, the electrons are subjected to a negativegradient in crossing the gap and are retarded so'th'at'they are directed along a .substantially.-sernicircuiar path --of somewhat smaller radiusithanthe p'ath traversed during the firstthalfcycle. noted? This actionsis repeated so that the electrons traverse semicircular paths of successively "decreasing.

radii until. they are collected by the collector 6180-? trode 24.

As is clear from the foregoing, at each crossing of the gap It the electronsnare subjected to a negative gradient so that, at each such crossing, they deliver a part of their energy to the oscillating circuit. Because of the nature of the radial gradient, described hereina'bove the time between successive crossings of the gap by the electrons is the same for all the semicircular paths traversed and, therefore, by deliveringtheir energy to the output circuit,-the electrons sustain-oscillation thereof at the frequencyto which it is tuned. 7

Although a specific embodimenteof this invention has been shown and described, it will be gap for projecting electricallycharged particles across said gap at a region removed from the center thereof, and' means' 'f'or causing "Said' particles torevolve about the transverse axis of said gap at: a prescribed frequency-and 'alon'g curved paths substantially concentric with said axis and of successively decreasing radius, said last means comprising electrodes adjacent said pair of electrodes and anenergizing sourcethere for for producing an electrostatic field having 1 with the relation circular-symmetry about saidaxis and a negative :radial gradient-.

4. Electric discharge apparatus comprising means for producing a circularly symmetrical electric" field having a radial gradient such that 1; the voltage at any point therem is in accordance- F Where'U'is'the voltage, r'is any radius and 'f is a prescribed frequency, means opposite the space in which said field obtains for injecting elec trons into said field tangentially thereto and with a': velocity corresponding "to a the fieldvoltage "at the point of injection of 'saidelectrons, a pair of I electrodes mounted on opposite sides of a plane transverse to said field, and 'a circuit connected '1' between said electrodes and tuned to said fre a understood that it is but illustrative and that e various modifications may be made'therein with out departing from the scope'and-spirit of this quency;

5. An electronic oscillation generator. comprise ing a pair of hollow electrodes mounted in juxtaposed spaced relation and boundi'ng fa'n operatinvention as defined in the appended claims.

For example, although the invention has been described with reference to a device utilizing electrons as the electrically charged particles, it is obvious that it may be practiced with devices employing ions. In this case, of course, the constant K in Equation 6 would be different, determined by the ion mass, and the requisite gradient would be correspondingly different.

What is claimed is:

1. Electric discharge apparatus comprising a pair of electrodes mounted in juxtaposition and bounding an operating region, a utilization circuit coupled to said electrodes, means for establishing in said region an electrostatic field having circular symmetry about the axis of said region and having a radial gradient such that the potential of said field varies proportionately to the square of radius from said axis, and means opposite said region for injecting a stream of electrically charged particles into said region adjacent the periphery thereof, substantially tangential thereto and with a velocit in electron volts substantially equal to the field voltage adjacent said periphery.

2. Electric discharge apparatus comprising a pair of hollow electrodes mounted in juxtaposition to define a gap therebetween, a tuned circuit connected between said electrodes, means for producing within the region bounded by said electrodes an electric field having circular symmetry about the transverse axis of said gap and varying radially proportionately both to the distance from said axis and to the resonant frequency of said circuit, and means opposite said gap for injecting into said region adjacent one end of said gap electrically charged particles having region, a tuned circuit connected between said electrodes, means for. producinginsaidre l.

gion an electrostaticfield circularly symmetrical about an axis passing between said electrodes and decreasing radially proportionately to ,1 being the resonant frequency of said circuit and 1' any radius, and means opposite said region for injecting electrons into said region, normal to said axis and. remote therefrom and with a velocity corresponding substantially to the field voltage at the point of their injection into said field.

6. An electronic oscillation generator in accordance with claim 5 wherein said field producing means comprises two groups of substantially semicircular field electrodes at opposite sides of said region and substantially concentric with said axis and resistance means interconnecting the field electrodes of each group.

'7. Electron discharge apparatus comprising a linear collector electrode, a pair of semicylindrical electrodes on opposite sides of said collector electrode and substantially coaxial therewith, a tuned circuit connected between said pair of electrodes, means for establishing in the region between said pair of electrodes an electrostatic field having circular symmetry about said collector electrode and having a radial gradient proportional to r being radius and being the frequency to which said circuit is tuned, and means opposite said region for projecting electrons into said field in the direction normal to said collector electrode and ata point'removed from said collector electrade and withia velocity corresponding to the field voltage at said point.

8. Electron discharge apparatus comprising a comprising two groups of semicircular field electrodes adjacent the ends of said pair of elec-- trodes and substantially concentric with said collector electrode and resistances interconnecting the field electrodes of each group with one another and said collector and pair of electrodes, and means opposite said region for projecting electrons into said field in the direction normal to said collector electrode and at a point removed fromsaid collector electrode and with a velocity corresponding to the field voltage at said point.

9. Electron discharge apparatus comprising a. pair of substantially semicylindrical electrodes having closed metallic ends and mounted in juxtaposed spaced substantially concentric relation and bounding a'substantially cylindrical space, a collector electrode extending along the axis of said space, one of said pair of electrodes having an aperturein the cylindrical wall thereof, a second collector electrode opposite said aperture, an electron gun adjacent one side of the other of said pair of electrodes and directed toward said opening, insulating members on the inner surfaces of the ends of said pair of electrodes, two similar groups of substantially semicircular field electrodes mounted on said insulating members and substantially concentric with respect to said first collector electrode, a utilization circuit connected between said pair of electrodes, means for producing in said space an electrostatic field having circular symmetry about said first collector electrode and a negative radial radient such that the field voltage at any point in said space is proportional to where f is a prescribed frequency and 1' is distance of the point from said first collector electrode, said last means comprising said field electrodes and resistances interconnecting the field electrodes of each group with one another and said first collector and pair of electrodes, and means connected to said gun and said pair of elec-* trodes for maintaining said gun and said pair of electrodes at substantially the same direct cur- ALBERT M. SKELLETT.

REFERENCES CITED The following references are of record in the 'file of this patent:

UNITED STATES PATENTS Number Name Date 1,870,888 Berthold Aug. 9, 1932 1,948,384 Lawrence Feb. 20, 1934 2,096,817 Malter et a1. Oct. 26, 1937 2,229,572 Jonas Jan. 21, 1941 2,242,888 Hollmann May 20, 1941 2,272,232 Wagner Feb. 10, 1942 2,289,756 Clavier et a1. July 14, 1942 2,293,417 Thompson Aug. 18, 1942 2,297,305 Kerst Sept. 29, 1942 2,390,701 Ferris Dec. 11, 1945 

